Underglaze decalcomania and method of making same



Jan. 2, 1962 J. GOBEL 3,015,574

UNDERGLAZE DECALCOMANIA AND METHOD OF MAKING SAME Filed March 31, 1958INVENTOR: JOHANNES GOBEL, BY

United States Patent Ofitice 3,015,574 Patented Jan. 2, 1962 3,015,574UNDERGLAZE DECALCOMANI'A AND METHOD OF MAKING SANEE Eohannes Giihel,Aschafienburg (Main), Germany, as-

signs: to Buntpapierfabrik A.G., Aschatfenburg (Main), Germany I FiledMar. 31, 1958, Ser. No. 724,819 Claims priority, application GermanyApr. 4, 1957 6 Claims. (Cl. 117--3.1)

The present invention relates to decalcomania, or transfer pictures ordesigns, and more particularly to decalcomania for ceramic underglazeapplication and the like.

For purposes of ornamenting china, stoneware, clay tile and the like,the ceramic industry uses decalcomania which are printed with ceramiccolors, assisted by suitable binders, on papers finished with specialmaterials.

The decalcornania may be printed directly on a socailed metapaperfinished with gum arabic, in which case a transfer lacquer is requiredfor purposes of transfer to the ceramic body. Printing, however, mayalso be efiected on skin paper. Skin paper is a transfer paper finishedwith a collodion film which on moistening of the carrier paper, can bewithdrawn therefrom. Finally, the transfer pictures or designs may beprinted on a paper finished with gum arabic, as in the first casementioned above, and the print can then be coated with a special lacquerwhich then serves as carrier for the printed picture or design andwhich, on the carrier paper having been thoroughly moistened, can bewithdrawn therefrom. Deealcomania of this kind can be used forunderglaze as well as upperglaze applications. For upperglazeapplication, the lacquer film carrying the picture is withdrawn orpulled away from the carrier paper and applied to the ceramic body theglaze of which is completely finished, and then fired at suitabletemperatures. For underglaze application, the film carrying the picture,applied to the porous ceramic body, must first be subjected to a bakingprocess, i.e. the organic substances of the binder and the lacquer filmmust be burned before the glaze suspension is applied. This is necessaryfor the reason that the binder and the lacquer film, because of theirhydrophobic characteristics, repel the aqueous glaze suspension so thatin the places ornamented by pictures, the glaze dispersion would notadhere, but after drying, would chip off again.

It is the principal object of the present invention to providedecalcomania for underglaze application which require a single firingprocess only, and which permit dispensing with the previously necessary,additional baking step for burning the organic substances of the binderand the picture carrying lacquer film.

Other objects, and the manner in which the same are attained, willbecome apparent as the specification proseeds.

The present invention contemplates methods of producing decalcomania forceramic underglaze application, by applying, in an optional sequence, ona carrier provided with a water soluble finish,

(a) The picture or design in ceramic colors, in a wellknown manner, bymeans of binders on the basis of varnishes, drying oils, or lacquers,and

(b) A film of carboxy group containing polyvinyl compounds, whereupon ifthe ceramic picture constitutes the top layer, this may be coated, ifdesired, by an additional film of carboxy group containing polyvinylcompounds, to serve as a masking lacquer. Consequently, the layers maybe arranged in any of the following sequences:

I. Carrier, polyvinyl film, ceramic picture, polyvinyl film (maskinglacquer).

Ii. Carrier, polyvinyl film, ceramic picture.

doctoring etc.

HI. Carrier, ceramic picture, polyvinyl film.

As the carrier, the invention may employ the well known papers which,for example, have been coated with gum arabic (meta-papers), or textilematerials coated with a water soluble layer. Foils of syntheticmaterials such as vinyl polymers, e.g polyvinyl chloride, or cellu losederivatives, such as cellophane, or foils of polyesters or epoxy resinsmay be used. In this case, a water soluble separating layer isunsuitable, a separating coat melting at elevated temperature on thebasis of hydrophilic waxes, such as polyethylene glycol being preferred.The water soluble coating may be dextrin, gum arabic or polyvinylalcohol, to mention a few examples.

As the vinyl polymers for the polyvinyl film, homopolymers, copolymersand polymeric mixtures of carboxy group containing vinyl compounds arecontemplated. Such carboxy group containing vinyl compounds include, forexample, acrylic acid, methacrylic acid, maleic acid etc. The copolymersor polymeric mixtures may contain other compounds compatible orsusceptible of being copolymerised with, the carboxy group containingvinyl compounds, such as polyacrylic acid ester, polymethacrylic acidester, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate,polwinyl alkyl ether, polyvinyl acetals, styrene etc. The only conditionto be fulfilled is that the copolymer or polymeric mixture is soluble,or swells, in water, or at least that it commences to swell in dilutealkaline solutions. The uppermost film serving as a masking lacquer, mayconsist of a homopolymer, copolymer or polymeric mixture of the samecomposition. The films may be applied, in the form of solutions ordispersions, by silk screen printing, or As the solvents or dispersingagents, e.g. alcohols, glycols, hydrocarbons, ketones, ethers, estersand water may be employed.

The ceramic picture is applied, in a manner known by itself, by silkscreen printing, lithography, or any other kind of printing; as thebinders, printing varnish, printing oils or other binders having alacquer base, may be used. For the ceramic colors and binders, allmaterials traditionally used for this kind of decalcomania may beemployed; for the colors, e.g. oxides and silicates, and for thebinders, e.g. those having a base of unsaturated oils, cellulose ethers,cellulose esters, higher by drocarbons; carboxy group containingpolyvinyl compounds are also suitable as binders.

The finished picture can be withdrawn from the carrier paper once thishas been moistened, and transferred onto the porous, non-glazed ceramicbody.

In order to ensure a perfect adhesion on the porous, non-glazed ceramicmass, the polyvinyl film, prior to application on the ceramic body, ispreferably activated by swelling in a mildly alkaline solution, such asa 1% solution of soda, whereby the sodium salts of the acids are formedcausing the film to become sticky, with the result that it firmlyadheres to the ceramic body and on drying, does not scale ofi" again.This activation of the film may be effected quite generally by means ofaqueous solutions of alkali hydroxides, alkali carbonates, ammonia,organic amines such as triethanol amine, and other alkaline substances.

A swelling of the film can also be effected by immersion in suitablesolvents, such as alcohols, e.g. methanol, ethanol etc., ketones such asacetone, others, eg diethyl ether, dibutyl ether etc. The activation maybe dispersed with and still, a perfect adhesion of the film on theceramic body obtained if the film is applied to the body under pressure.

The picture bearing film is withdrawn from the carrier and dried on'theceramic body, whereupon in the usual manner, a glaze suspension isapplied by immersion or spraying. Once the water has evaporated, theceramic body is fired as usual, in a mufile oven, at temperatures fromabout 1000 to 1200 C. The organic material of the polyvinyl filmdepolymerises when heated to about 400 C., and evaporates when furtherheated to about 500 C., i.e. at temperatures below the sintering pointof Example 1 kg. polymethacrylic acid (a low viscosity grade) aresuspended in 95 l. of water whereupon 3 l. of ammonia of are added. Thesolution obtained is applied by means of a doctor on a paper prepared bymeans of gum arabic. After drying, the film is lightly sprayed, forhardening purposes, with a 5% solution of aluminum sulphate and againdried. The film of polymethacrylic acid ammonium thus prepared isimprinted with ceramic colors in a well known manner. In order totransfer the film onto the ceramic body, paper-and film are moistenedwith water and the paper is placed, with the side bearing the film, onthe ceramic body. Once the film has become adsorbed on the porousceramic body, the carrier paper is withdrawn. An activation in aseparate step is not necessary in this case. After firing in aconventional manner, an excellent underglaze picture is obtained.

The polymethacrylic acid used for the polyvinyl film, may also bereplaced by a copolymer of 90% of methacrylic acid and 10% of vinylacetate, or else, a homopolymer of acrylic acid may be employed to equaladvantage.

ExdmpieZ A lacquer mixture is prepared according to the following'prescription:

18 kg, of a copolymer of of methacrylic acid and 65% of methacrylic acidmethylester 61.5 kg. of ethylglycol 20.5 kg. of tetralin 35.7 kg. ofpolyvinylmethyl ether (K=) of 70%,

dissolved in toluene This lacquer solution is applied by silk-screenprinting, on a carrier paper prepared with dextrin, using a fine silkgauze having 100 meshes per cm On this film there is applied a picturein ceramic, annealable colors, in the usual manner either by silk-screenprinting or lithoprinting.

After drying, the picture can be transferred on a nonglazed ceramicbody. For this purpose, the picture with the carrier paper is immersed,for activation purposes, for 10-15 seconds, in an 0.2% aqueous solutionof triethanol amine. The picture, which has commenced to swell, isapplied on a ceramic body which, because of its porosity, adsorbs thepicture so that, following a brief application of pressure, it firmlyadheres thereto. Subsequently the carrier paper is withdrawn. Thepicture is dried and the ceramic body immersed in the glaze material inthe usual manner, or else the glaze material is sprayed on the ceramicbody. The glaze material is permitted to dry whereupon the glazedceramic body is placed in the kiln. The baking is effected at atemperature of 1100 C.

Example 3 A lacquer mixture according to Example 2 is prepared anddried, in the manner described with reference to Example 2, on a carrierconsisting of a fine, dense, cotton fabric prepared by means of gumarabic whereupon the ceramic picture is applied as noted with referenceto Example 2. On this picture, another film is applied by silk-screenprinting to serve as a masking lacquer. For this film the same lacquermixture is employed as for the film disposed underneath the ceramicpicture. The further treatment follows the directions of Example 2, theresult being as excellent as that obtained by Example 2.

This method may also be modified by the inclusion of an activation usinga mixture of ethanol and Water. The same excellent results are obtained.The fabric carrier may be replaced by a paper prepared by means of gumarabic.

Example4 A lacquer mixture according to Example 2 is used and applied,in the manner described with reference to Example 2, on a carrierconsisting of a polyvinyl chloride foil coated with polyethylene glycol(melting point 65 C.) and on which the ceramic picture was applied asdescribed wtih reference to Example 2. The application to the non-glazedcermic body as well as the further treatment follows the directions ofExample 2, with equally excellent results.

Example 5 a A ceramic picture is printed on a paper coated with gumarabic (a so-called meta-paper), and on this pic ture, a film is appliedfrom a solution of 20 kg. of polyacrylic acid in a mixture of 40 kg. ofethanol and 40 k of methanol by silk-screen printing. The finishedicture with the film is withdrawn from the paper, activated by immersionin a 1% soda solution and then applied to the ceramic body to beornamented, whereupon the glaze suspension is sprayed thereon. A single,conventional baking step then yields an excellent underglaze picture. 7

Instead of the aforenoted homopolymer of polyacrylic acid, copolymers ofacrylic acid with 10, 25 or 33% of vinyl chloride may be used for thepolyvinyl film, with equally advantageous results.

Example 6 A solution of a copolymer of maleic acid anhydride, vinylacetate and vinyl chloride (acid No.=l2) in an ester mixture, is appliedby a doctor on a carrier paper coated with gum arabic, whereupon aceramic picture is applied by silk-screen printing. The paper isremoved, the picture activated in a 1% aqueous solution of alkalicarbonate to which 20% of acetone is added, and is then applied to thestill unglazed ceramic body. P01- lowing a conventional baking step, thethoroughly ex cellent underglaze picture is obtained.

Example 7 In accordance with Example 1, the solution of polymethacrylicacid in ammonia (or a corresponding solu- Example 8 A lacquer mixtureaccording to Example 2 was used and applied on a polyvinyl chloride foilwhich had been coated with polyethylene glycol (melting point of 65 C.).Subsequently, the ceramic picture was applied and the further treatmenteffected as described with reference to Example 4. An excellentunderglaze picture was obtained.

In the place of the lacquer mixture according to Exam- Plc 2, aCOpQlyrner according to Example 6, or a methacrylic acid homopolymeraccording to Example 1 may also be used. Also, an additional polyvinylfilm serving as a masking lacquer may be applied on the ceramic picture.The underglaze pictures obtained are of excellent quality in any ofthese instances.

The invention is illustrated further by the drawing accompanying thisspecification and forming part thereof.

In the drawing:

FIG. 1 is a diagrammatic representation of a multilayer decalcomaniaaccording to the invention;

FIG. 2 is a similar showing of a modification, and

FIG. 3 is a similar showing of still another embodiment of theinvention.

Referring to the drawing, and first to FIG. 1, this shows a multi-layerdecalcomania comprising a top layer in the form of a hydrophilic maskingcoating 1, containing a film forming ingredient consisting of ahydrophilic polymer according to the invention, a design or picturelayer 2 in ceramic color containing varnish, drying oil or similarbinder, disposed underneath the coating 1, a water soluble coating 3 ofdex-trin or the like arranged below the picture layer 2, and a carrier 4e.g. of paper constituting the bottom layer.

In the embodiment of the invention illustrated in FIG. 2, layers 5 and 7are hydrophilic masking coatings containing a film forming ingredientaccording to the invention, which are disposed above and below theceramic color design coating 6, the base being again composed of a watersoluble coating 8 on a carrier 9 such as paper.

The modification shown in FIG. 3 has the ceramic color design coating 10disposed at the top, a hydrophilic masking coating 11 containing a filmforming ingredien-t located underneath the design layer 11, the basecomprising the Water soluble coating 12 on a paper or similar carrierlayer 13.

The underglaze decalcomania according to the invention have the signaladvantage that they have hydrophilic characteristics with the resultthat when the moist glaze material is applied on the decalcomania, it isnot repelled so that the glaze may be directly applied on the picturewithout a previous baking process such as was necessary up to now. Thisadvantage is particularly important as it implies the saving of anentire operation inasmuch as the annealing process is eliminated, theorganic substance of the novel lacquer film according to the inventionbeing burnt only during baking of the glaze. Accordingly, the novelmethod requires for the entire operation of applying the ornamentationand applying the glaze, a single baking process only. The glaze adheresto the places ornamented with the present decalcomania just as well asto other parts of the ceramic body which are not so ornamented. Thepictures obtained after baking display no step at the margin, but blendbeautifully with the glaze applied on top thereof.

I wish it to be understood that I do not desire to be limited to theexact details of procedure, composition or application as modificationswithin the scope of the appended claims and involving no departure fromthe spirit of the invention nor any sacrifice of the advantages thereof,may occur to workers in this field.

I claim:

1. The method of preparing a ceramic decalcornania, comprising applyinga water soluble base coating on strong carrier paper, said water solublecoating selected from the group consisting of dextrin, gum arabic, watersoluble starch, polyvinyl methyl ether and polyvinyl alcohol, thereaftercoating a design in ceramic color, said ceramic color being in the formof a liquid composition containing a binder selected from the groupconsisting of varnish, drying oil and lacquer, then applying ahydrophilic masking coating over the ceramic design, said maskingcoating containing a film forming ingredient consisting of a hydrophilicpolymer selected from the group consisting of polyacrylic acid,polymethacrylic acid and maleic acid polymer and copolymers of saidacids with a substance selected from the group consisting of polyvinylchloride, polyvinylidene chloride, polyvinyl acetate, polyvinyl alkylether, polymethacrylic acid ester, polyacrylic acid ester, polyvinylacetals and styrene.

2. A decalcomania comprising a strong carrier paper, a water solublereleasable base coating on said strong carrier paper, said base coatingselected from the group consisting of dextrin, gum arabic, water solublestarch, polyvinyl methyl ether, and polyvinyl alcohol, a ceramic colordesign coating on said base coating containing a ceramic coloringmaterial in a binder selected from the group consisting of varnish,drying oil and lacquer, and a hydrophilic masking coating over the saidceramic design coating, said masking coating containing a film formingingredient consisting of a hydrophilic polymer selected from the groupconsisting of polyacrylic acid, polymethacrylic acid and maleic acidpolymers and copolymers of said acids with a substance selected from thegroup consisting of polymethacrylic acid ester, polyacrylic acid ester,polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate,polyvinyl alkyl ether, polyvinyl acetals and styrene, said maskingswelling in water and dilute alkali to adhere to an unglazed surface ofa ceramic base and provides a decorative film by a single firingoperation after upper glaze application.

3. -A decalcomania as claimed in claim 2 wherein said polymer ispolyacrylic acid.

4. A decalcomania as claimed in claim 2 wherein said polymer ispolymethacrylic acid.

5. A decalcomania as claimed in claim 2 wherein said polymer is apolymer of maleic acid.

6. A decalcomania as claimed in claim 2 wherein said masking coatingunderlies as well as covers said ceramic color design coating.

References Cited in the file of this patent UNITED STATES PATENTS1,976,679 Fikentscher et al. Oct. 9, 1934 2,629,679 Rathke Feb. 24, 1953FOREIGN PATENTS 13,083 Great Britain Aug. 10, 1905 427,405 Great BritainApr. 17, 1935 690,623 Great Britain Apr. 22, 1953

1. THE METHOD OF PREPARING A CERAMIC DECLCOMANIA COMPRISING APPLYING AWATER SOLUBLE BASE COATING ON STRONG CARRIER PAPER, SAID WATER SOLUBLECOATING SELECTED FROM THE GROUP CONSISTING OF DETRIN, GIM ARABIC, WATERSOLUBLE STARCH, POLYVINYL METHYL ETHER AND POLYVINYL ALCOHOL, THEREAFTERCOATING A DESIGN IN CERAMIC COLOR, SAID CERAMIC COLOR BEING IN FORM OF ALIQUID COMPOSITION CONTAINING A BINDER SELECTED FROM THE GROUPCONSISTING OF VARNISH, DRYING OIL AND LACQUER, THEN APPLYING AHYDROPHILLIC MASKING COATING OVER THE CERAMIC DESIGN, SAID MASKINGCOATING